Design, Synthesis, Crystal Structure, and Thermal Studies of Ni_0.779SbF₃(SO₄): A New Electrode Material for Electrochemical Supercapacitors

Abstract

A new transition-metal-based antimony fluoride sulfate compound, Ni 0.779 SbF 3 (SO 4 ), has been studied, which appears to be a promising candidate for an electrode material in supercapacitor devices. The hydrothermal synthetic technique has been employed for growing single crystals. The single-crystal X-ray diffraction study reveals that it crystallizes in the orthorhombic space group Cmce with unit cell parameters a = 15.1710 ( 3) Å, b = 7.1843 (11) Å, and c = 11.070 (17) Å and Z = 8. The crystal structure consists of a [SbF 3 O 2 ] polyhedron and a [SO 4 ] tetrahedron along with cis-and trans-[NiO 4 F 2 ] octahedrons of two different Ni atoms that result in negatively charged [NiSbF 3 • SO 4 ] n layers in the crystal structure, where each layer is made up of chains of [Ni(1)O 6 F 2 ] n , [Ni(2)O 8 F 2 ] n , and [(SbF 3 ) 2 (SO 4 ) 2 ] n4− . The partial occupancy on Ni sites resulted in the compound being nonstoichiometric. The morphological analysis by both scanning electron microscopy (SEM) and tunneling electron microscopy (TEM) reveals a multilayer dense nanoflake-like morphology. Thermogravimetric analysis (TG-DTA) shows that the compound has a high thermal stability with a decomposition temperature above 450 °C. The density functional theory (DFT) and density of states (DOS) are found to be commensurate with the experimental results. The material shows good electrochemical performance with a capacitance of 245 F g −1 at a specific current density of 1 A g −1 . Further, the electrochemical impedance spectroscopy (EIS) study confirms the capacitive nature of the electrode.

CuAs2O4: Design, Hydrothermal Synthesis, Crystal Structure, Photocatalytic Dye Degradation, Hydrogen Evolution Reaction, Knoevenagel Condensation Reaction, and Thermal Studies

“…The overall water splitting reaction requires an energy input of Δ G = 237.1 kJ/mol at standard conditions, which corresponds to a thermodynamic voltage requirement of 1.23 V. These oxides are also used in ion storage batteries. Examples of a few transition metal oxides include BiVO 4 , BiFeO 3 , NiCr 2 O 4 , CuCo 2 O 4 , NiCo 2 O 4 , CuO/CuBi 2 O 4 , Ag/CuCo 2 O 4 , NiO/NiCo 2 O 4 , [M = Fe, Co, Ni, and Mn], Co 3 Sb 4 O 6 F 6 , CoMo 2 Sb 2 O 10 , Ni 0.779 SbF 3 (SO 4 ), which have recently drawn remarkable attention as electrocatalysts. − …”